Quiet hydraulic depression-elevation drive for sonar transducer reflector independently rotatable ina zimuth



- Nov. 7, 1967 s. BARON 3,351,897

QUIET HYDRAULIC DEPRESSION-ELEVATION DRIVE FOR SONAR TRANSDUCERREFLECTOR INDEPENDENTLY ROTATABLE IN AZIMUTH Filed March 11, 1966 4Sheets-Sheet 1 3,351,897 QUIET HYDRAULIC DEPRESSION-ELEVATION DRIVE FORSONAR S. BARON Nov. 7, 1967' TRANSDUCER REFLECTOR INDEPENDENTLYROTATABLE IN AZIMUTH 4 Sheets-Sheet 2 Filed March 11, 1966 INVENTOR.

SID/V5 Y B/QRON Nov. 7, 1967 s BARON 3,351,897

QUIET HYDRAULIC DEPRESSION-ELEVATION DRIVE FOR SONAR TRANSDUCERREFLECTOR INDEPENDENTLY ROTATABLE IN AZIMUTH Filed March 11, 1966 4Sheets-Sheet 5 l{l:| I l I INVENTOR.

S/DNEY B/QEON BY 4 02- 411M017 Ham/7 Fl T TOR/V5 Y.

1 6 s. BARON 3,351,897

, QUIET HYDRAULIC DEPRESSION-ELEVATIONDRIVE FOR SONAR TRANSDUCERREFLECTOR INDEPENDENTLY ROTATABLE IN AZIMUTH Filed March 11, 1966 4Sheets-Sheet 4 S/DNEY BARON LZA/JMUL 1 e m/L QTTO/ZNEY United StatesPatent M 3,351,897 QUIET HYDRAULIC DEPRESSION-ELEVA- TIGN DRIVE FORSONAR TRANSDUCER REFLEQTOR INDEPENDENTLY RGTATA- BLE IN AZHMUTH SidneyBaron, New London, Conm, assignor to the United States of America, asrepresented by the Secretary of the Navy Filed Mar. 11, 1966, Ser. No.535,303 4 Claims. (Cl. 340-) The invention described herein may bemanufactured and used by or for the Government of the United States ofAmerica for governmental purposes without the payment of any royaltiesthereon or therefor.

This invention relates to improvements in training mechanisms for anunderwater acoustic transducer-reflector assembly.

A transducer-reflector assembly that has been in use heretofore on asubmarine includes a drive shaft that extends from within the submarineapproximately vertically through a water-tight bearing arrangement inthe pressure hull of the submarine and is coupled to azimuthal trainingmechanism inside the submarine. A mounting yoke is secured to the end ofthe drive shaft outside the hull. A cylindrical transducer is secured tothe yoke perpendicular to the drive shaft. The axis of the drive shaftintersects the center of the axis of the transducer. A cylindricalparabolic underwater acoustic reflector is secured to the yoke alongsidebut spaced from the transducer and with the focal line of the reflectorand the axis of the transducer coincident. The reflector is surfacedwith any conventional underwater acoustic reflector mate-rial orcommercially marketed underwater acoustic reflector material e.g.Goodrich Isoper, cemented on a rigid aluminum frame that shapes thereflector material to define a parabolic reflecting surface. In use theassembly is selectively oriented in azimuth, and while in a selectedazimuthal orientation, pulse power in the lower audio frequency range issupplied to the transducer. The transducer-reflector intercepts echoesof the projected pulsed acoustic power. Additionally thetransducer-reflector may intercept other waterborne acoustic energy inthe same frequency range including energy which originates as noise andvibration generated by the azimuthal training mechanism for the driveshaft. The azimuthal training mechanism for the transducer-reflector isdesigned for quiet operation.

Longer distance echo ranging is now carried out by directing theprojected acoustic energy for bouncing 0d the bottom to a target areaand then listening for echoes returned by a target via the bottom. Thedepression angle at which the reflector is set is a function of desiredrange, the distance of the transducer-reflector assembly from thebottom, and the distance of the target from the bottom. To adapt theabove-described transducer-reflector assembly for use in the bottombounce mode, the reflector requires means for adjusting the reflectorangularly about the axis of the transducer. Mechanisms for training indepression-elevation are known. For example, gun mounts include a pinionand sector gear. However, depression-elevation adjusting mechanismsknown heretofore are too noisy in the lower audio range for thefollowing reason. Acoustic energy projected via the bottom bounce modeand the corresponding echoes returned via the bottom bounce mode do nottraverse the same path due to the bending action of the water. After apulse of acoustic energy is projected in the bottom bounce mode, thedepression-elevation angle of the reflector needs to be adjusted to thedepression angle along which a target echo might be returned or needs toscan a range of depression angle to search for an echo.

Patented Nov. 7, 1967 If substantial noise is generated by thedepression-elevation angle adjustment mechanism and delivered to thewater during the time following a projected pulse corresponding to therange of interest echoes of the noise may be returned as a spurioustarget or may be returned at the same time that an echo might bereturned from a target in the selected target area. Noise is emittednon-directionally and thus noise emitted after the pulse may 'bereflected from an obstruction at much shorter range than the selectedtarget area. Noise echoes returned from a short range may havesufficient amplitude to register as a spurious target or to mask an echofrom a more distant target and even if no echo is returned from a targetthe doubt introduced by the noise seriously interferes with theecho-ranging. If the circuitry is in the listen mode when the depressionangle of the reflector is changing, any noise generated by the change isdetected directly.

An object of this invention is to provide a quiet depression-elevationtraining mechanism for a transducerreflector assembly independentlytraina'ble in azimuth.

Other objects and advantages will appear from the following descriptionof an example of the invention, and the novel feature will beparticularly pointed out in the appended claims.

FIGS. 1 and 2 are front and rear perspective views of atransducer-reflector assembly including part of a hydraulicdepression-elevation training means in accordance with this invention,

FIG. 3 is a view on an enlarged scale partly in section and partly inelevation of the rotary coupling in FIG. 2 including adjacent parts, and

FIG. 4 is a schematic hydraulic diagram of the depression-elevationangle adjusting system.

In FIGS. 1 and 2 there is shown an underwater acoustictransducer-reflector assembly 10 that is trainable in azimuth andwherein the reflector is trainable in depressionelevation. The assembly10 includes a rigid framework having a pair of substantially identicalspaced parallel vertical supports 12 rigidly joined near their bottomends by a pair of horizontal pipes 14. A cylindrical elongate transducer16 is secured to the upper ends of the vertical supports 12 and acylindrical parabolic reflector 18 is journalled on the upper ends ofvertical supports 12. The axis of the transducer 16 and the focal lineof the parabolic reflector are coincident. The assembly 10 is secured toan end of a vertical shaft 20 by means of structural means 22 secured tointermediate portions of pipes 14. The axis of the shaft 20 intersectsthe axis of transducer 16. The shaft 20 extends through water-tightbearing means, not shown, in the pressure hull of the submarine, and isconnected to azimuth drive means, not shown, inside the submarine fortraining or continuously rotating the assembly in azimuth.

The transducer 16 comprises one or a plurality of inline segmentedcylinder transducers of the type disclosed in US. Patent 3,043,967. Abrace 24 secured to the structural means 22 and including a circularmember 26 intermediate the ends of the transducer assembly and avertical member 28 adds support to the transducer.

Each of the vertical supports 12 includes a pancakeshaped container 30supporting inductors, not shown, therein in an oil filled environmentfor resonance with the capacitance of the electrostrictive transducer atthe design frequency. Electrical cables 32 connect the transducer andinductors and extend through the shaft 20 which is hollow to slip ringson the shaft inside the submarine, as is conventional.

Flexible hydraulic conduit means 40 and 42 communicate with oppositeends of the cylinder.

A rotary hydraulic coupling 44 is supported above the assembly coaxialwith the shaft 20. A vertical rod 46 is secured to the circular member26 and to one part of.

coupling 44. The vertical member 28 and the rod 46 extend throughelongated slots 48 and 50 in the reflector.

The rotary coupling 44 includes an outer collar-shaped part 52 and aninner cylindrical part 54 journalled therein and secured to vertical rod46. The inner part has two coaxial integral portions of differentdiameters defining a bearing face therebetween for engaging theouterpart. The outer part is formed with opposed axially spaced radialbores 60 and 62 for conduits 92 and 94. Fluid passages 68 and 70 areformed in the inner part 54 in fluid communication with the bores 60 and62. The smaller diameter portion of the inner part is formed withcircular grooves 72 and 74 in fluid communication with the passages 68and 70. The fluid passages 68 and 70 terminate in bores that seat pipefitting terminations 56 and 58 on the ends of hydraulic conduit means40, 42. Three circular grooves 76, 78, 80 formed in the smaller diameterportion of the inner part seat O-ring seals. The smaller diameterportion of the inner part is slightly longer than the outer part wherebya disk 82 secured coaxially to the end of the smaller diameter portionretains the outer part on the inner part but does not impede relativerotation. A flat annulus 84 having thickness equal to the thickness ofthe disk 82 plus the difference in length between the outer part and thesmaller diameter portion of the inner part is bolted to the end of theouter part coaxial therewith and concentric with the disk 82. Theannulus 84 serves as securing means to a support above the assembly.Only so much of the hydraulic conduit means 40 and 42 is flexible as isneeded for relative movement between cylinder 34, and the supportstructure. The remainder of the hydraulic conduit means 40 and 42.between the cylinder 34 and the inner part of the rotary coupling may berigid piping to minimize transfer of acoustic energy by the hydraulicfluid to the water.

An electrical device 86 responsive to vertical orientation is secured tothe reflector for providing an output which is a function of theorientation of the reflector in depressionelevation angle. Device 86 mayinclude a potentiometer having an arcuate resistor element and a pivotalgravityresponsive pendulum-operated tap electrically connected by meansof leads extending through the shaft 20, and slip rings on the shaftinside the submarine, not shown, to a direct current source and acalibrated meter inside the submarine in a simple inexpensive resistancemeasuring arrangement for indicating depression-elevation angle of thereflector. Conventional servo techniques can be included to maintainconstant a selected reflector angle.

An essentially noise-free hydraulic system for adjusting the reflectorin depression-elevation is shown in FIG. 4. The rotary hydrauliccoupling 44 couples the opposite ends of cylinder 34 to a pump 90 and toa high pressure hydraulic supply, not shown. Hydraulic conduit means 92,94 extend between the rotary hydraulic coupling and the high pressuresupply and pump 90 respectively. The pump is driven by a reversibleelectric motor 96. Pressure relief valves 98 and 160 are connectedbetween the conduit 92, 94 to limit the pressure differential when thepiston reaches a limit of travel in cylinder 34. An accumulator 102having air therein is connected to the hydraulic conduit 94 between thepump and rotary hydraulic coupling; the pump is operated to raise orlower the pressure in the conduit 94 relative to the on-board highpressure supply. The accumulator allows for change in volume ofhydraulic fluid as the piston rod in the cylinder 34 moves between theinside of the cylinder and the water. The accumulator also functions asan acoustic capacitive loading chamber to minimize pump pressurepulsation. The hydraulic conduits 92, 94 include short lengths offlexible tubing 104, 106 adjacent the pump to reduce hydraulic soundtransmission. Because the depression-elevation angle adjustment means isoperated at high pressure, pump noise is minimized; a major part of pumpnoise is caused by low suction pressure. High operating pressure has thefurther advantage of overcoming sea water pressure on the exteriorpiping, part of which is rubber tubing, and also prevents reaction onthe piston in the hydraulic cylinder 34.

Preferably the pump is a reversible hydraulic angle pump with aplurality of pistons for gradual piston action e.g. a commerciallymarketed Vickers angle pump with nine pistons, for low noise. The motorshall have sleeve bearings rather than ball bearing to reduce noise. AV- belt coupling between motor and pump is preferable because itcontributes to vibration-isolation. Vibrationisolation mountings for themotor and for the entire hydraulic assembly in the submarine alsoreduces noise.

This depression-elevation adjustment means described is simple,reliable, quiet, enables continuous adjustment and provides anindication of the orientation on board the submarine. It does notgenerate interfering noise during operation in the listening mode.

It will be understood that various changes in the details, materials andarrangements of parts (and steps), which have been herein described andillustrated in order to explain the nature of the invention, may be madeby those skilled in the art within the principle and scope of theinvention as expressed in the appended claims.

I claim:

1. An underwater acoustic transducer assembly that is trainablerelatively noiselessly comprising:

a cylindrical transducer,

a cylindrical parabolic reflector of approximately the same length assaid transducer,

means mounting said cylindrical transducer and journalling saidparabolic reflector in spaced parallel coextensive relationship with theaxis of the cylindrical transducer and the focal line of the parabolicreflector coincident,

a shaft secured at one end to said mounting means with the axissubstantially perpendicular to the axis of the cylindrical transducerand the focal line of the reflector,

means journalling said shaft vertically,

a hydraulic cylinder and a piston reeiprocable therein and a piston rodextending from the piston through one end of the cylinder, the other endof the cylinder and the free end of the piston rod being pivotallyjoined to said mounting means and said reflector for angularly adjustingsaid reflector about the transducer axis and focal line of thereflector,

a fluid coupling having coaxial relatively rotatable parts for providingcontinuous fluid communication between respective pairs of hydraulicconduits independently of relative angular orientation of the partsmounted above said reflector coaxial with said shaft,

rigid means secured to said mounting means and to one part of said fluidcoupling,

said reflector being slotted transversely to its length for providingclearance therethrough for said rigid means over a range of angularorientation of the reflector relative to said mounting means, said rigidmeans extending through the slotted portion of the reflector,

fluid conduits extending between the fluid coupling and opposite ends ofsaid cylinder, and

a hydraulic system connected to the fluid coupling for selectivelyestablishing a pressure differential across said cylinder for adjustingthe depressionelevation angle of the reflector.

2. An underwater acoustic transducer assembly as defined in claim 1wherein said hydraulic system includes:

a reversible motor-driven pump,

a pair of conduits connecting the pump and rotary coupling,

pressure relief valve connected between the pair of conduits,

a high pressure source connected to one of said conduits, and

an air accumulator connected to the other conduit between the rotarycoupling and the pressure relief valves.

3. An underwater acoustic transducer assembly as defined in claim 1further including electrical means for providing information of theangular orientation of the reflector.

4. An underwater acoustic transducer assembly as defined in claim 1wherein:

one part of the coupling is collar-shaped and has two ports that extendradially through longitudinally spaced portions thereof and areapproximately opposite relative to the axis of the rotary coupling, theother part of the coupling has a cylindrical portion of slightly greaterlength than the length of the one part and terminates at a step oflarger transverse dimension for seating the one part, the surface of thecylindrical portion of the other part has two circular grooves inregistration with the ports of the one part and has packing between andpacking on opposite sides of two grooves that register with the ports inthe one part,

means on the two parts retaining the two parts in assembled relativelyrotatable relationship,

said other part also having approximately opposite ports beyond itscylindrical portion joined by internal hydraulic passages to said twocircular grooves.

References Cited UNITED STATES PATENTS 11/1957 Smaltz et a]. 1810.56/1962 Lasky et a1. 3405

1. AN UNDERWATER ACOUSTIC TRANSDUCEER ASSEMBLY THAT IS TRAINABLERELATIVELY NOISELESSLY COMPRISING: A CYLINDRICAL TRANSDUCER, ACYLINDRICAL PARABOLIC REFLECTOR OF APPROXIMATELY THE SAME LENGTH AS SAIDTRANSDUCER, MEANS MOUNTING SAID CYLINDRICAL TRANSDUCER AND JOURNALLINGSAID PARABOLIC REFLECTOR IN SPACED PARALLEL COEXTENSIVE RELATIONSHIPWITH THE AXIS OF THE CYLINDRICAL TRANSDUCER AND THE FOCAL LINE OF THEPARABOLIC REFLECTOR COINCIDENT, A SHAFT SECURED AT ONE END TO SAIDMOUNTING MEANS WITH THE AXIS SUBSTANTIALLY PERPENDICULAR TO THE AXIS OFTHE CYLINDRICAL TRANSDUCER AND THE FOCAL LINE OF THE REFLECTOR, MEANSJOURNALLING SAID SHAFT VERTICALLY, A HYDRAULIC CYLINDER AND A PISTONRECIPROCABLE THEREIN AND A PISTON ROD EXTENDING FROM THE PISTON THROUGHONE END OF THE CYLINDER, THE OTHER END OF THE CYLINDER AND THE FREE ENDOF THE PISTON ROD BEING PIVOTALLY JOINED TO SAID MOUNTING MEANS AND SAIDREFLECTOR FOR ANGULARLY ADJUSTING SAID REFLECTOR ABOUT THE TRANSDUCERAXIS AND FOCAL LINE OF THE REFLECTOR, A FLUID COUPLING HAVING COACIALRELATIVELY ROTATABLE PARTS FOR PROVIDING CONTINUOUS FLUID COMMUNICATIONBETWEEN RESPECTIVE PAIRS OF HYDRAULIC CONDUITS INDEPENDENTLY OF RELATIVEANGULAR ORIENTATION OF THE PARTS MOUNTED ABOVE SAID REFLECTOR COAXIALWITH SAID SHAFT. RIGID MEANS SECURED TO SAID MOUNTING MEANS AND TO ONEPART OF SAID FLUID COUPLING, SAID REFLECTOR BEING SLOTTED TRANSVERSELYTO ITS LENGTH FOR PROVIDING CLEARANCE THERETHROUGH FOR SAID RIGID MEANSOVER A RANGE OF ANGULAR ORIENTATION OF THE REFLECTOR RELATIVE TO SAIDMOUNTING MEANS, SAID RIGID MEANS EXTENDING THROUGH THE SLOTTED PORTIONOF THE REFLECTOR, FLUID CONDUITS EXTENDING BETWEEN THE FLUID COUPLINGAND OPPOSITE ENDS OF SAID CYLINDER, AND A HYDRAULIC SYSTEM CONNECTED TOTHE FLUID COUPLING FOR SELECTIVELY ESTABLISHING A PRESSURE DIFFERENTIALACROSS SAID CYLINDER FOR ADJUSTING THE DEPRESSIONELEVATION ANGLE OF THEREFLECTOR.